When to Confirm a Positive NAAT An additional test should be considered after a positive screening test if a false-positive screening test would result in substantial adverse medical, social, or psychological impact for a patient. Screening Tests To Detect Chlamydia trachomatis and Neisseria gonorrhoeae Infections-2002, MMWR 2002; 51 (No. RR-15): 14

NAATs Confirmation Recommendation Consideration should be given to routine additional testing for persons with positive C. trachomatis or N. gonorrhoeae screening tests when risk factor information or actual surveys indicate that the prevalence is low, resulting in a lower PPV (e.g., <90%) Screening Tests To Detect Chlamydia trachomatis and Neisseria gonorrhoeae Infections-2002, MMWR 2002; 51 (No. RR-15): 14

Interactions Between Specificity and PPV Specificity = 99.5% Sensitivity = 90.0% (top) Sensitivity = 80.0% (bottom) Specificity = 99.0% Sensitivity = 90.0% (top) Sensitivity = 80.0% (bottom)

NAATs Confirmation Recommendation Only another NAAT is sufficiently sensitive to be used as a confirmatory test for a NAAT Note: Such an approach has received only limited evaluation. Screening Tests To Detect Chlamydia trachomatis and Neisseria gonorrhoeae Infections- 2002, MMWR 2002; 51 (No. RR-15): 14

Controversies In STD Diagnostics Confirmatory Testing Is Required For Positive NAATs for Chlamydia and Gonoccocal Infections in Populations with less than 4% prevalence